An oxygen absorbent is a small bag with a content that reacts with oxygen and consumes it. The absorbents are delivered vacuum-packed in an airtight bag. They are completely safe to use when storing food as they do not contain any toxic substances.


How oxygen absorbers work

Oxygen absorbers (also called oxygen eaters) consume oxygen chemically. The small cardboard wrapped bags contain 80% iron filings and 20% activated carbon. As soon as a bag is exposed to air, the binding begins. The iron rusts and that process consumes the oxygen. If this is done in a small, closed, airtight environment, all the oxygen will be used up. This takes a couple of hours. If you feel the bag where the oxygen absorber is located, you will feel that it is getting warm.

Why oxygen absorbers?

Oxygen is an ingredient of life, but is also destructive on a molecular level. Oxygen is the cause of rust formation, yellowing of newspapers and discolouration of silver.
Oxygen also spoils food, either through oxidation or through oxygen-dependent organisms spoiling the food. It manifests itself through unpleasant changes in taste, texture, appearance and nutritional value. These risks are avoided with oxygen absorbers in completely sealed packages.
In addition, the oxygen-free environment effectively kills any potential insects, larvae and eggs within days. 

To counteract this, oxygen absorbers should be used when food is to be stored for the long term.

Air consists of 21% oxygen. When you seal a mylar bag with an oxygen absorbent in it, the air in the bag is reduced by about 21%. The remaining gases (mainly nitrogen, 78%) are completely harmless for e.g. food stored in the bag. An oxygen-free mylar bag of food will not look like a vacuum-packed bag, but will shrink somewhat depending on the amount of air in the bag and what you are packing. If you squeeze as much air as you can out of a bag of peas or rice before you seal it again, it will be vacuum-packed, whereas oatmeal rarely is, even if both bags are oxygen-free and the contents are protected.

Here you can read more about storage in an oxygen-free environment 

Store your oxygen absorbers in an airtight glass jar with a rubber seal. Then you can easily use them as you need. 
The bag also contains an oxygen indicator (see picture 3). This is pink as it is not in contact with oxygen. If oxygen gets into the bag, it turns purple. If you store your oxygen absorbers in a patent-type glass jar, put this over the jar, then you will see if your oxygen absorbers are fresh or if oxygen has leaked in..